code: def test_valid_negation():
      q = Quantity(ETH, 5)
      neg_q = -q
      assert neg_q == -5
  
imports: import pytest
  import unittest.mock
  from tensortrade.oms.instruments import *
  from tensortrade.core.exceptions import *
label_desc: Use image node_id 23 for calling a global function with example usage: test_valid_negation() without return types